There are various reasons for counting and tracking the number of rounds fired from a gun or large caliber armament piece. Inventory control of ammunition, maintenance schedules, personnel training, and so forth, are generally all a factor of the number of rounds discharged from the weapon. For larger caliber pieces, such as field cannons, artillery pieces, and ship mounted guns, the barrel of the weapon is generally limited to a specified number of uses, and it is important from operational and safety considerations not to exceed this specified number.
In this regard, various mechanical and electrical counter devices have been described in the art for the purpose of tracking the number of rounds fired from a piece of armament. For example, U.S. Pat. Nos. 4,102,074 and 4,146,987 describe an impulse activated counter for weapons that includes an actuator having a reactive weight with an eccentric center of mass. The weight is freely rotatable in a plane within preset limits in response to an externally applied impulse force. The weight applies a torque force to a shaft that, in turn, activates the counter. Means are provided to apply a counter torque to the weight so that the counter is actuated only in response to a resultant torque of a predetermined magnitude generated by the impulse.
U.S. Pat. No. 3,453,882 describes a device to determine when a projectile emerges from the muzzle of a gun. The device records the signal from an electrical circuit containing a photo-duo-diode located in a radial hole near the muzzle of the gun. The signal is recorded as a reference along with a time base, gun chamber pressure, and other data.
The device of U.S. Pat. No. 3,552,053 counts shots fired from a gun by way of a piezo-electric crystal that is clamped to the barrel of the gun. Upon discharge of a shot, the crystal is stressed by transient radial expansion of the barrel and produces an electrical output pulse that is sensed by a threshold detector and counted in a register. U.S. Pat. No. 6,817,239 describes another device that utilizes a piezofilm sensor integrated into a circuit board mounted onto a gun. The piezofilm sensor is deformed by the impulse recoil of the gun and emits a signal to a chip contained in the circuit board, which records the impulse as a count.
U.S. Pat. No. 3,792,638 describes a fluidic artillery round counter that measures the zone charge used to fire the artillery rounds. The device includes a check valve, a capacitance volume, a regulator, a fluidic oscillator, and a counter whose output is fed into a mechanical summing register. The check valve is connected to the gun bore through a small tube, and gas from the gun bore is the actuating source for the device.
Although the above cited patents have suggested various types of counters, the need still exists for a highly reliable yet simple counting mechanism that can withstand the rigors and extreme conditions of a battlefield environment. This need is particularly acute for large caliber guns, such as cannons and artillery pieces.